The A To Z Of Building Your Own Keyboard

July 3, 2018 by Tom Nardi 6 Comments

We’ve featured a number of people who’ve taken the plunge and created their own customized keyboard; at this point it’s safe to say that there’s enough information and source code out there that anyone who’s looking to build their own board won’t have much trouble figuring out how to do so. That being said, it’s nice to have a comprehensive at a process from start to finish. Why sift through forum posts and image galleries looking for crumbs if you don’t have to?

That’s precisely what makes this write-up by [Maarten Tromp] so interesting. He walks the reader through every step of the design and creation of his customized keyboard, from coming up with the rather unique layout to writing the firmware for its AVR microcontroller. It’s a long read, filled with plenty of tips and tricks from a multitude of disciplines.

After looking at other custom boards for inspiration, [Maarten] used OpenSCAD to create a 3D model of his proposed design, and had it printed at Shapeways. His electronics are based around an Atmel ATMega328P using vUSB, and Microchip MCP23017 I/O expanders to connect all the keys. He wrapped it all up by designing a PCB in gEDA PCB and having it sent off for production. As a testament to his attention to detail, everything mated up on the first try.

[Maarten] is happy with the final product, but mentions that in a future revision he would like to add RGB lighting and use a microcontroller that has native USB support. He’d also like to drop the I/O expanders and switch over to Charlieplexing for the key matrix.

From uncommon layouts to diminutive technicolor beauties, it seems there’s no end of custom keyboards in sight. We aren’t complaining.

PCB Holder Quick-fix Turns Out To Be Big Improvement

July 1, 2018 by Donald Papp 15 Comments

When something needs improving, most hacks often make a small tweak to address a problem without changing how things really work. Other hacks go a level deeper, and that’s what [Felix Rusu] did with his 3D printed magnetic holders. Originally designed to address a shortcoming with the PCB holders in his LE40V desktop pick-and-place machine, they turned out to be useful for other applications as well, and easily modified to use whatever size magnets happen to be handy.

The problem [Felix] had with the PCB holders on his pick-and-place was that they hold the board suspended in midair by gripping the sides. The board is held securely, but the high density of parts on panelized PCB designs leads to vibrations in the suspended board as the pick-and-place head goes to work. Things are even worse when the board is v-scored for the purpose of easily snapping apart the smaller boards later; they sometimes break along the score lines due to the stress.

Most people would solve this problem by putting a spacer underneath the board to stabilize things, but [Felix] decided to go a level deeper and change the mounting system altogether with a simple mod. The boards now lie on a flat metal plate, and his magnetic holders are simple to make and easily do the job of holding any size PCB secure. As a bonus, it turns out that the holders also do a passable job of holding work materials down on a laser cutter’s honeycomb table. A video overview is embedded below, and the design files are available on Thingiverse.

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Gyrotourbillion Blesses The Eyes, Hard To Say

June 30, 2018 by Lewin Day 14 Comments

Clock movements are beautifully complex things. Made up of gears and springs, they’re designed to tick away and keep accurate time. Unfortunately, due to the vagaries of the universe, various sources of error tend to creep in – things like temperature changes, mechanical shocks, and so on. In the quest for ever better timekeeping, watchmakers decided to try and rotate the entire escapement and balance wheel to counteract the changing effect of gravity as the watch changed position in regular use.

They’re mechanical works of art, to be sure, and until recently, reserved for only the finest and most luxurious timepieces. As always, times change, and tourbillions are coming down in price thanks to efforts by Chinese manufacturers entering the market with lower-cost devices. But hey – you can always just make one at home.

That’s right – it’s a 3D printed gyrotourbillion! Complete with a 3D printed watch spring, it’s an amazing piece of engineering that would look truly impressive astride any desk. All that’s required to produce it is a capable 3D printer and some off-the-shelf bearings and you’ve got a horological work of art.

It’s not the first 3D-printed tourbillion we’ve seen, but we always find such intricate builds to be highly impressive. We can’t wait to see what comes next – if you’re building one on Stone Henge scale for Burning Man, be sure to let us know. Video after the break.

[Thanks to Keith for the tip!]

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XLIDAR Is A Merry-Go-Round Of Time-Of-Flight Sensors

June 29, 2018 by Donald Papp 38 Comments

[JRodrigo]’s xLIDAR project is one of those ideas that seemed so attractively workable that it went directly to a PCB prototype without doing much stopping along the way. The concept was to mount a trio of outward-facing VL53L0X distance sensors to a small PCB disk, and then turn that disk with a motor and belt while taking readings. As the sensors turn, their distance readings can be used to paint a picture of the immediate surroundings (at least within about 1 meter, which is the maximum range of the VL53L0X.)

The hardware is made to be accessible and has a strong element of “what you see is what you get.” The distance sensors are on small breakout boards, and the board turns the sensor disk via a DC motor and 3D printed belt drive. Even the method of encoding the disk’s movement and zero position has the same WYSIWYG straightforwardness: a spring contact and an interrupted bare copper trace on the bottom of the sensor disk acts as a physical switch. In fact, exposed copper traces in concentric circular patterns and spring pins taken from an SD card socket are what provide power and communications as the disk turns.

The prototype looks good and sounds like it should work, but how well does it hold up? We’ll find out once [JRodrigo] does some testing. Until then, the board designs are available on the project’s GitHub repository if anyone wants to take a shot at their own approach without starting from scratch.

3D Printed Tourniquets Are Not A Cinch

June 28, 2018 by Brian McEvoy 32 Comments

Saying that something is a cinch is a way of saying that it is easy. Modeling a thin handle with a hole through the middle seems like it would be a simple task accomplishable in a single afternoon and that includes the time to print a copy or two. We are here to tell you that is only the first task when making tourniquets for gunshot victims. Content warning: there are real pictures of severe trauma. Below, is a video of a training session with the tourniquets in Hayat Center in Gaza and has a simulated wound on a mannequin.

On the first pass, many things are done correctly: the handle is the correct length and diameter, the strap hole fit the strap, and the part is well oriented on the platen. As with many first iterations, it looks good on a screen, but in the real world, we all live under Murphy’s law. In practice, some of the strap holes had sharp edges that cut into the strap, and one of the printed buckles broke unexpectedly.

On the whole, the low cost and availability of the open-source tourniquets outweigh the danger of operating without them. Open-source medical devices are not just for use in the field, they can help with training too. This tourniquet is saving people and proving that modeling skills can be a big help in the real world.
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Servo Becomes Mini Linear Actuator

June 2, 2018 by Donald Papp 11 Comments

RC servos are a common component in many robotics projects, but [Giovanni Leal] needed linear motion instead of the rotary actuation that servos normally offer. The 3D Printed Mini Linear Actuator was developed as a way to turn a mini servo into a linear actuator, giving it more power in the process.

A servo uses a potentiometer attached to the output shaft in order to sense position, and the internal electronics take care of driving the motor to move the shaft to the desired angle. [Giovanni] took apart an economical mini servo and after replacing the motor with a 100:1 gear motor and using it to power a compact 3D printed linear actuator, he used the servo’s potentiometer to read the linear actuator’s position. As a result, the linear actuator can exert considerably more force than the original servo while retaining exactly the same servo interface. You can see one being assembled and tested in the video embedded below, which is part of [Giovanni]’s entry for The 2018 Hackaday Prize.

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Bike Helmet Plays Music Via Tiny Motors For Bone Conduction

June 2, 2018 by Donald Papp 20 Comments

[Matlek] had an interesting problem. On one hand, a 40 minute bike commute without music is a dull event but in France it is illegal for any driver to wear headphones. What to do? Wanting neither to break the law nor accept the risk of blocking out surrounding sounds by wearing headphones anyway, and unwilling to create noise pollution for others with a speaker system, [Matlek] decided to improvise a custom attachment for a bike helmet that plays audio via bone conduction. We’ll admit that our first thought was a worrisome idea of sandwiching metal surface transducers between a helmet and one’s skull (and being one crash away from the helmet embedding said transducers…) but happily [Matlek]’s creation is nothing of the sort.

A 3D printed rack and pinon provides adjustability and stable contact with the “sweet spot” behind each ear.

The bone conduction is cleverly achieved by driving small DC motors with an audio signal through a TPA2012 based audio amplifier, which is powered by a single 18650 cell. By using motors in place of speakers, and using a 3D printed enclosure to hold the motors up to a sweet spot just behind the ears, it’s possible to play music that only the wearer can hear and does not block environmental sounds.

[Matlek] didn’t just throw this together, either. This design was the result of researching bone conduction audio, gathering a variety of different components to use as transducers, testing which performed best, and testing different locations on the body. Just behind the ear was the sweet spot, with the bony area having good accessibility to a helmet-mounted solution. Amusingly, due to the contact between the motors and the rest of the hardware, the helmet itself acts as a large (but weak) speaker and faint music is audible from close range. [Matlek] plans to isolate the motors from the rest of the assembly to prevent this.

Another good way to get audio to transmit via bone conduction? Send it through the teeth. While maybe not the best option for a bike rider, biting down on this metal rod sends audio straight to your inner ear.